-# Set this to 'yes' to enable PAM authentication (via challenge-response)
-# and session processing. Depending on your PAM configuration, this may
-# bypass the setting of 'PasswordAuthentication' and 'PermitEmptyPasswords'
+# Set this to 'yes' to enable PAM authentication, account processing,
+# and session processing. If this is enabled, PAM authentication will
+# be allowed through the ChallengeResponseAuthentication mechanism.
+# Depending on your PAM configuration, this may bypass the setting of
+# PasswordAuthentication, PermitEmptyPasswords, and
+# "PermitRootLogin without-password". If you just want the PAM account and
+# session checks to run without PAM authentication, then enable this but set
+# ChallengeResponseAuthentication=no